论文标题
盖亚相距蜗牛的起源和命运
The origin and fate of the Gaia phase-space snail
论文作者
论文摘要
Gaia蜗牛是太阳邻居星的分布，位于银河中部平面正常的速度方面的螺旋特征。蜗牛可能是由于引力干扰的相位混合而引起的，这些干扰在遥远的过去扰动了椎间盘。最常见的假设是，最强烈的干扰是由于靠近太阳能邻居的射手座矮星银河的通道所引起的。在本文中，我们调查了蜗牛是由许多小型干扰而不是一个大的蜗牛产生的替代假设，即引力潜能中的高斯噪声。大部分噪音可能是由于黑色晕圈中的子结构引起的。我们表明，该假设自然地再现了蜗牛的大多数特性。特别是在没有免费参数的情况下，它可以正确预测蜗牛的明显年龄为$ \ sim 0.5 $ gyr。该模型的一个重要组成部分是，无论其原因如何，任何类似蜗牛的特征都被巨大的分子云或其他小规模结构散射在时间尺度$ \ sillesim 1 $ gyr上所消除。
The Gaia snail is a spiral feature in the distribution of solar-neighbourhood stars in position and velocity normal to the Galactic midplane. The snail probably arises from phase mixing of gravitational disturbances that perturbed the disc in the distant past. The most common hypothesis is that the strongest disturbance resulted from a passage of the Sagittarius dwarf galaxy close to the solar neighbourhood. In this paper we investigate the alternative hypothesis that the snail is created by many small disturbances rather than one large one, that is, by Gaussian noise in the gravitational potential. Probably most of this noise is due to substructures in the dark-matter halo. We show that this hypothesis naturally reproduces most of the properties of the snail. In particular it predicts correctly, with no free parameters, that the apparent age of the snail will be $ \sim 0.5$ Gyr. An important ingredient of this model is that any snail-like feature in the solar neighbourhood, whatever its cause, is erased by scattering from giant molecular clouds or other small-scale structure on a time-scale $\lesssim 1$ Gyr.
